Gloria, it's become very familiar for this president over the past four and a half years, going out and trying to comfort the nation.

GLORIA BORGER, CNN CHIEF POLITICAL ANALYST: Sadly, it has become familiar. Wolf, you go back to 2009, you had Fort Hood. You had Tucson with the Gabby Giffords shootings. In 2012, you had Aurora, Colorado. You had Newtown in 2012 also.

This is -- presidents are always the "pastor-in-chief" to a certain degree, but I think President Obama has had to do more than his share of this.

Of course, you know, as a result, he's been talking about gun control and trying to deal with that.

Of course, he hasn't been able to do it, so what I think we saw on his face yesterday was a real sense of sort of frustration, which is sadly, again, I'm having to do this.

BLITZER: You know, yesterday he was scheduled to give a speech on the fifth anniversary of the collapse of the economy, basically, and how the economy has improved over the past five years.

He delayed it for about an hour. He eventually did it. He opened with those remarks about what happened in the shooting.

But then he went on to severely criticize the Republicans, and he's being criticized himself today for maybe miscalculating, suggesting -

BORGER: Being a little tone deaf.

BLITZER: -- maybe he shouldn't have done it.

BORGER: Yeah. I think it's really hard, and I think either you do it or you don't do it.

I don't think there would have been any problem in putting off that speech for a day or two and saying, you know what, today we have to take a moment. We have to think about the people at the Navy Yard. We have to think about what's going on there.

And then come out into the Rose Garden maybe later this week or next week and talk about the economy.

It's clear the president was trying to take a pivot. He also talked about Syria.

But you know, you muddle your message, Wolf, and I think the public was really focused on what was going on at the Navy Yard, and as a result, I think everything he wanted to say on the economy kind of gets lost, and he looks kind of discordant.

BLITZER: We'll continue this conversation later in "THE SITUATION ROOM." Gloria, thanks very much.

Here's more of what we're working on this hour here in the NEWSROOM.

We have new details from the United Nations report on the use of chemical weapons in Syria, including the size, the shape, the direction of the weapons.

The forensic evidence of the attack, that's coming up, also, much more on the Washington Navy Yard shooting.

(COMMERCIAL BREAK)

BLITZER: Let's get some more now on those U.N. weapons inspectors' report on last month's chemical weapons attack in Syria.

The U.N. says it's the worst use of weapons of mass destruction in this, the 21st century.

CNN analyst David Kay is a former United Nations weapons inspector. He's joining us here in Washington.

You know, I want to get to this report in a second, but you have security clearances, and I'm sure you have top, top, top secret security clearances.

We were -- I was talking with Barbara Starr earlier about contractors getting security clearances from other contractors as opposed to government officials.

You know something about this.

DAVID KAY, CNN ANALYST: Well, the background checks, all the work that leads to a conclusion that you should or should not have a contract has been outsourced. It's been outsourced for a number of years to do the work.

BLITZER: Outsourced to other contractors.

KAY: To other contractors.

BLITZER: It's pretty shocking to me that they would trust contractors to give security clearances.

KAY: And, you know, part of the Washington ethos, a belief in the air, is that contractors are cheaper than federal employees.

A, I doubt that that is true, but there are a lot of work contracted out these days.

BLITZER: All right, let's talk about this U.N. report. You're an expert on this.

Walk us through the highlight. What was the most important thing that jumped out at you?

KAY: A, that sarin was much better than the Iraqis had used. It was weapons-grade sarin.

The amount, one warhead contained as much as 56 liters. That's 15 gallons, about 150 pounds of sarin.

The timing of the attack was absolutely professional. You want to use chemicals either in the early morning hours, preferably, or late in the evening because it's heavier than air. It goes where the people are hiding.

And, actually, the most surprising thing, I think surprising to the Russians, the inspectors were able to get the azimuth of two of the warheads, the path they flew.

It only takes basic trigonometry, as the "New York Times," Human Right Watch has done. Any number of people have today. It goes back to a government military base.

BLITZER: So what jumped out at me, there were two types of rockets that were used.

KAY: Yes, one was Russian. That's the one with the serial labeling. That's a relatively small one, probably no more than nine liters of sarin in that one.

But there was one, this design is well-known as a rocket. It's designed by the Iranians.

Who knows who produced it? But it contained this much larger and actually crude but clever warhead around it.

BLITZER: And, you know, what was fascinating to me in trying to review what was going on, it left no doubt to me who was responsible, although the U.N. inspectors' report itself, they could not say who did it. That wasn't their mandate.

KAY: The reason they couldn't say is the Security Council said, "Thou shalt not, that's not your job."

But what they did, very cleverly, is give you the azimuth of two of the warheads. That allows anyone who got through high school trig to figure out where it came from.

BLITZER: The chances that the rebels actually were the ones responsible -- as the Syrian regime insists, as the Russians insist, and Putin in the article in "The New York Times," he said the rebels did this.

The chances based on the forensic evidence, everything you saw in this United Nations weapons inspectors' report says to you -

KAY: It was carried out by the government. There's no doubt about this.

You'd have to believe that the rebels operated inside a very tightly controlled Syrian military base with very large rockets, and fired at multiple positions and had access to probably 350 liters of sarin.

Not possible. This was a government carried out attack.

BLITZER: The Russians and the Syrian regime, they continue to insist it was the rebels, but everybody now know the truth.

KAY: I don't think that gives them any more credibility.

BLITZER: Yeah, David Kay, thanks very much.

KAY: Thank you.

BLITZER: Families have been fleeing the civil war in Syria since it began. Refugee camps have sprung up in neighboring countries.

In today's "Impact Your World," UNICEF ambassador Lucy Liu sends out a call for help for children who have left their homes.

(BEGIN VIDEO CLIP)

LUCY LIU, UNICEF AMBASSADOR: Hi, I'm Lucy Liu, and we can make an impact for Syrian children.

There is civil war going on that is creating absolute pandemonium, and people are fleeing into Lebanon, into Jordan, into Iraq.

These children are suffering. They have lice, they have scabies and they've lost family. They can't go to school.

They're not getting the medical attention they need. They're not getting the nutrition they need. There's going to be a lost generation of children if this continues.

Children deserve to have a childhood. What happens on the other side of the world isn't just their business, it's our business, because we share the same water, we share the same environment.

If we understand that we are actually one community, then it makes the world so much smaller and much more tangible for people to understand.

UNICEF is currently desperate for donations for Syria. It's our duty as human beings to give back.

Join the movement, "Impact Your World," CNN.com/impact.

(END VIDEO CLIP)

BLITZER: Go ahead, do it. Good idea. Thank you, Lucy.

Investigators have recovered three guns -- three guns -- from yesterday's shooting rampage. We're taking a closer look how many weapons the shooter actually had access to.

We'll speak to Senator Richard Blumenthal who earlier this year wanted universal background checks after the tragic mass shooting at the Sandy Hook Elementary School in Connecticut.

(COMMERCIAL BREAK)

WOLF BLITZER, CNN ANCHOR: The shooting rampage at the Washington Navy Yard yesterday sadly just the latest of many massacres across the country in recent years. Get this, there have been more than 200 mass killings in the United States since 2006. A mass killing is the murder of four or more people. Each shooting spree reignites the gun debate in the United States.

Here we are once again. Twelve people were killed by a gunman here in Washington yesterday and lawmakers are demanding action. Senator Richard Blumenthal of Connecticut is one of them. He's joining us from Capitol Hill right now.

Thanks very much, senator, for joining us.

I know you're a member of the Senate Armed Services Committee. And lots of questions about these military contractors getting security clearances and that other contractors may be giving them these security clearances. I assume you're outraged by what's going on.

SEN. RICHARD BLUMENTHAL (D), CONNECTICUT: I am outraged and I think that there are a lot of facts that we still need to know as with all the ongoing investigation. But certainly the mental health aspect of this senseless, horrific tragedy ought to be front and center and a basis for action. This mass tragedy another in a series that you've covered, Wolf, and you and I were together in Sandy Hook, ought to be a call to action.

And, of course, attention to the military contractors. These civilian employees, sometimes with questionable qualifications and background, ought to be overseen and scrutinized more completely and comprehensively and vigorously. So I think there's an area where outrage is certainly the right emotion.

BLITZER: Here's another thing that -- and you're a veteran -- that bothers me. He was cited for misconduct when he was in the Navy eight times, but he receives an honorable discharge, not a general discharge, not a dishonorable discharge, but an honorable discharge. Can you explain that?

BLUMENTHAL: Again, there are facts that we'll need to know before we draw conclusions, but the question of whether an honorable discharge was justified here and the consequences of that honorable discharge in enabling him to have the position of trust that gave him clearance, whether that security badge enabled him to have access to this facility is still an open question. How he got the weapon that he used initially, whether it was a shotgun, all of these questions come back to some fundamental facts that we need to know.

But overriding here, there ought to be a call to action. Dr. Orlowski yesterday at the MedStar Washington Medical Center I think put it best. If we don't do something, shame on us. And I'm hoping that my colleagues will be shaken by how close physically this mass shooting was to them. We had to lockdown the Senate for a period of a couple of hours. Every one of us ought to feel that our lives are touched by it.

BLITZER: I know when we met in Newtown under horrible circumstances at the massacre at the Sandy Hook Elementary School, I think you - you thought there would be a decent chance there would be stricter gun control legislation enacted. That hasn't happened. There -- certainly hasn't happened in the House of Representatives. What are the prospects, from your standpoint, of tighter gun laws going forward right now in the aftermath of what happened in Washington yesterday? BLUMENTHAL: I think mental health and an initiative to provide more mental health care and opportunities for preventive action ought to be the centerpiece of what we do going forward. Clearly, that is a common theme to Sandy Hook, as you know, from covering Adam Lanza and the background there, and this tragedy involving somebody who clearly was severely troubled, if not disturbed mentally. And so I think background checks, combined with mental health, there are ways to bring together the political consensus that we need. And after all, 90 percent or more of the American people support these common sense initiatives. Many of them gun owners ,and in fact, many NRA members themselves.

So my hope is, by the end of the year, or certainly by the end of this session, we will have some kind of common sense measure. We came so close, 55 votes there, and we needed 60. The majority of the Senate were ready to vote and 54 did vote for background checks. So I'd like to see those measures come back.

BLITZER: Yes, it's a tougher -- I'm sure it's a tougher battle, it will be, in the House of Representatives as well. But as you say, you got votes, not enough to beat a filibuster in the Senate.

Senator Blumenthal, thanks very much for joining us.

BLUMENTHAL: Thank you, Wolf.

BLITZER: During the chaos of yesterday's attack at the Navy Yard here in Washington, many families waited for hours to find out if their loved ones were OK. Up next, we're going to show you some of the emotional reunions.

(COMMERCIAL BREAK)

BLITZER: All day Monday, busloads of Navy Yard workers arrived at Washington Nationals Park. That's where police set up a staging area. It's only a few blocks from the Navy Yard. Some had to wait for hours to hear about their loved ones inside the Navy Yard. Kris Van Cleave of our affiliate station WJLA caught up with some families as they reunited.

(BEGIN VIDEOTAPE)

KRIS VAN CLEAVE, WJLA REPORTER (voice-over): Tears of joy meet sobs of relief Monday evening as Trisina Steiger Smith (ph) reunited with her husband William after spending the day locked down inside a Navy Yard office building. A touching reunion for the newlyweds after hours of fearing the worst.

UNIDENTIFIED FEMALE: It's been a really rough day.

VAN CLEAVE (on camera): How good does it feel to have her in the car and taking her home?

Many victims, obviously, shaken by the horror of the day, saying they were simply so glad and relieved the day was over.

Evacuees in Colorado are starting to return home after devastating floods, but some are finding nothing left at all. We'll have the latest on the damage. That's next.

(COMMERCIAL BREAK)

BLITZER: In Colorado, the skies are clearing, flood waters are receding, but sadly the death toll has been on the rise. Eight people have died, more than 600 are missing or not accounted for. There are still entire towns cut off by floodwaters. Bridges are washed out. Kelly Hunt returned home today and was just crushed at what she saw.

(BEGIN VIDEO CLIP)

KELLY HUNT, FLOOD VICTIM: Today is our first day up here since we've been evacuated. And I feel like it's worse than I thought it would be. We lost absolutely everything we owned.

(END VIDEO CLIP)

BLITZER: Nearly 18,000 homes around the state have been damaged.

That's it for me. Thanks very much for watching. I'm Wolf Blitzer in Washington. Join me again 3:00 p.m. Eastern in the NEWSROOM, later 5:00 p.m. Eastern in "The Situation Room." Jake Tapper and Brooke Baldwin pick up our coverage right now.